In this paper, we present a highly sensitive long period grating (LPG) with a unique double-cladding layer structure including an ultra-thin inner silica cladding layer and a low refractive index liquid crystal outer cladding layer. By using an ultra-thin cladding layer (28 μm in diameter) reduced by chemical etching, the LPG has a single resonant band over a wide range of wavelength and higher sensitivity to the environmental refractive index change. In addition, the high thermal-optic effect of liquid crystal makes it very easy to tune the resonant wavelength by controlling the temperature of the liquid crystal. Thus, a highly sensitive tunable filter can be made. The experimental results show that a tuning efficiency of 2.1 nm/°C is achieved. To the best of our knowledge, this is the highest tuning efficiency ever reported.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering